A NetWork Entry (NWE) procedure is a procedure that takes place whenever a mobile station (MS) starts to communicate with a base station (BS), whether it is due to a new connection (NWE), re-connecting, and every HandOver (HO) during which the MS switches from being served by one BS to being served by another.
The NWE procedure involves determining how the MS and the respective BS would recognize each other, and how to enable the MS to obtain downlink synchronization with the BS. FIG. 1 demonstrates a typical NWE procedure known in the art which is held between MS 100 and BS 150, operating in accordance with the WiMAX Recommendation. During the first phase of the process the MS receives parameters to be used in transmitting and receiving uplink and downlink communications. Uplink synchronization is obtained by the MS performing a ranging process with BS 150, and adjusting its transmission power. During the procedure, MS 100 transmits a Ranging Request (RNG-REQ) message to BS 150 (step 113), and BS 150 transmits a Ranging Response (RNG-RSP) message to MS 100 (step 115) in response to the RNG-REQ message received thereat.
Upon performing the ranging operation as described above, MS 100 transmits a Subscriber Station Basic Capability Request (SBC-REQ) message (step 117) to BS 150 in order to receive the basic capabilities available for the communications between the BS and the MS. The SBC-REQ message, which is a Medium Access Control (MAC) type of message that MS 100 transmits to BS 150 includes among others, information on a Modulation and Coding Scheme (MCS) level supportable by the MS. Upon receipt of the SBC-REQ message from the MS, BS 150 detects an MCS level supportable by the MS included in the received SBC-REQ message, and transmits a Subscriber Station Basic Capability Response (SBC-RSP) message to MS 100 (step 119) in reply to the SBC-REQ message. The procedure then continues by authenticating and registering the MS and thereafter the MS is serviced by the BS 150.
One of the problems associated with wireless networks is recovery in a case where communications are received as corrupted packets which cannot be properly interpreted and consequently, it is not possible to use the data sent by the other side. Repetitive transmissions of the same data are often of little help because the conditions which caused the corruption of the first attempt are likely to corrupt the repeated attempts as well. HARQ (Hybrid Automatic Repeat ReQuest) is a technique that was set up to enable faster recovery from errors in wireless networks, and it involves storing corrupted packets (referred to by the IEEE 802.16e Recommendation as sub-bursts) that have been received from an identified given MS in the receiving BS rather than discarding them. This provides the capability that even if retransmitted packets are received at the BS with errors, still, a good packet can be derived by combining two or more bad ones. HARQ procedure may be utilized on both data connections and management connections (Basic and Primary connections) and enables to gain from the combining of the sub-bursts additional 10 log10(Nsub-bursts) dB for each retransmission. However, one of the problems associated with this procedure is that it cannot be carried out for messages exchanged during certain steps of the handshake process between the MS and the BS. FIG. 2 illustrates for which of the steps HARQ may not be implemented, and for which of the steps HARQ may be utilized in the way explained above. Also, there are some further network protocols which have not been initially designed for re-transmission of messages.
FIG. 3 illustrates such an HARQ operation in the uplink (UL) direction. In this case BS 350 instructs MS 300 to re-transmit the sub-burst until the combining of packets is successful. MS 300 transmits in step 311 a message to BS 350 which is received in a corrupted shape (due to any one or more of various reasons such as fading, weak signal, increased interference and the like), a message that is transmitted during one of the stages illustrated in FIG. 2, where HARQ may be implemented. Therefore, in step 313 BS 350 transmits a ReTX-REQ (re-transmission request) to MS 300 informing the latter that its previous message has not been successfully received. Once the MS receives the ReTX-REQ, it transmits in step 315 a ReTX-RSP (re-transmitting response), one which is basically the same message transmitted in step 311. Let us assume that the re-transmitted messages is also received in a corrupted shape, then, since BS 350 has the required knowledge on the identity of the transmitting MS 300 it is capable of combining these two corrupted messages. If the BS succeeds in combining the two messages transmitted in steps 311 and 315 it uses the combined message, but in case where the BS 350 cannot combine the two message into a complete meaningful message, it would transmit again a ReTX-REQ until either the original message is restored or until the number of allowed retransmissions is exhausted (and then the sub-burst is dropped).
Unfortunately, there are several scenarios in the art in which the HARQ is not applicable:                During network entry (NWE) procedure as described in FIG. 1 as prior to the completion of this NWE procedure, the BS is unable to identify the given MS and consequently the BS is unable to combine two or more messages of unknown origin. An underlying assumption for the HARQ process to be effective is that the packets being combined are received from the same source (MS), and if the MS is unidentifiable, the HARQ procedure cannot be activated.        When the HARQ capabilities of the subscriber are unknown to the BS.        During network re-entry (HO and link-loss) ranging transactions, due to the fact that ranging procedure is carried out anonymously.        When the subscriber does not support HARQ operation over management connections. In this case HARQ will not be activated at all on control transactions messages.        
Several references are known in the art for utilizing HARQ to improve the transmission QoS. US 2008310338 for example, discloses a method for configuring an acknowledgement mode of an HARQ re-transmission protocol which is used for acknowledging the delivery of data packets of a service provided from a transmitting entity to a receiving entity in a wireless communication.
Another example is US 2006104242 which discloses a method for transmitting and receiving downlink control information in a mobile communication system. In order to transmit data packet in an HARQ mobile communication system, a second transceiver receives an RG as rate control information from a first transceiver. The second transceiver then sets the allowed maximum data rate of an HARQ process and transmits packet data within the allowed maximum data rate to the first transceiver.
However none of these solutions are effective in overcoming the above problems when the HARQ process as explained above cannot be implemented. Thus, the present invention seeks to provide a solution to these unsolved problems.